When (in what book) does Odysseus start to change and lose his ego (hubris)?
The term “hubris” in ancient Greek does not mean “ego” or “arrogance”. Instead, it refers to specific actions, legally similar to what in the contemporary world would be called “aggravated assault.” A typical instance of such an action is the maiming of Polyphemus, son of Poseidon. Arrogance, though, does go hand in had with such acts; Odysseus’ shout out his name and gloating after the escape would be an example of adding insult to injury.
One characteristic feature of epic is that, as Bruno Snell suggests, it does not include character development in the modern sense, nor a great deal of internal awareness, but rather shows characters from an external point of view as performing actions.
In you are looking for character transformation, the closest instance might be when Odysseus cries in Book VIII.